1. Field of the Invention
The present invention relates to an evaluating method of a hydrophobic process with respect to a substrate such as a semiconductor wafer, a glass substrate for a liquid crystal display, and the like, and relates to its apparatus, and a resist pattern forming system.
2. Description of the Related Art
A mask for forming a circuit pattern on a surface of a semiconductor wafer (hereinafter referred to as a wafer) or an LCD substrate can be obtained in such a way that the surface of the substrate such as wafer is coated with a photoresist solution (hereinafter referred to as a resist), and the resist-coated surface is subjected to irradiation such light, and a developing process. In order to prevent a resist mask from being peeled off the substrate at the time of a developing step, ion implantation thereafter or etching, it is important to improve adhesion between the substrate and the resist.
For this reason, for example, the surface of the substrate is subjected to the hydrophobic process before being coated with the resist. The hydrophobic process is that the substrate is put in an airtight container and a hydrophobic process gas of HMDS (hexamethyldisilazane:(CH3)3SiNHSi(CH3)3) vapor is supplied into the airtight container to be brought in contact with the substrate while the substrate is held heated at about 90 to 100xc2x0 C. Hydrophobic nature of the surface of the substrate is thus enhanced whereby improving adhesion between the substrate and the resist.
In order to improve adhesion between the substrate and the resist, it is necessary to judge the corresponding adhesion by some way. In conventional, the hydrophobic (or hydrophilic) nature of the surface of the substrate before being subjected to the resist coating was generally measured to judge the corresponding adhesion. As a method for judging the hydrophobic nature, there is a method in which a contact angle of a drop of water dropped on the surface of the substrate is measured as an index of the hydrophobic nature. The contact angle refers to an angle obtained by doubling the angle, which a line connecting a top portion of the water droplet on the substrate of a target object to an outer periphery of the droplet onto the surface forms with the surface. Hydrophobic process conditions are adjusted based on the value of the contact angle thus obtained so as to improve the adhesion. However, the method for examining the hydrophobic nature of the substrate using the above-mentioned measurement of the contact angle has the following problem.
More specifically, the drop of water must be dropped onto the surface of the substrate, serving as a non-measuring object, in order to measure the contact angle. There is a case in which organic contaminants are put on the substrate and the contact angle of only the corresponding portion increases, with the result that it is judged that the apparent hydrophobic process is performed to the substrate. Even in this case, the substrate does not undergo a silylation reaction in some cases. The same is applied to the performance of an over-silylation process. In such a case, predetermined adhesion strength of the substrate cannot be obtained, and this causes a pattern peeling, so that hydrophobic optimization cannot be performed.
An object of the present invention is to provide a technique in which a hydrophobic nature of the corresponding surface of the substrate can be examined with high reliability by measuring an amount of hydrophobic process gas on the surface of the substrate.
In order to attain the above object, according to the first aspect of the present invention, there is provided an evaluating method of a hydrophobic process state of a hydrophobic process section in a resist pattern forming apparatus having the hydrophobic process section for supplying a hydrophobic process gas to a surface of a substrate to provide a hydrophobic process to the corresponding surface thereof, a coating process section for coating the surface of the substrate with a resist, and a developing process section for supplying a developing solution to the surface of the substrate subjected to exposure to light, the method comprising the steps of: transferring the substrate subjected to the hydrophobic process by the hydrophobic process section to an analyzing section; and detecting components of the hydrophobic process gas on the surface of the substrate subjected to the hydrophobic process at the analyzing section, whereby performing measurement of a relative detection value of the hydrophobic process gas on the surface of the substrate.
According to this method, since the components of the hydrophobic process gas on the surface of the substrate is analyzed, measurement of hydroscopic gas on the surface of the substrate can be performed without having an influence of organic material adhered to the surface of the substrate during the transfer. Also, the hydrophobic process state can be evaluated accurately. Accordingly, for example, it is possible to adopt the correlation data having high reliability between the quantity of the hydrophobic process gas on the surface of the substrate and the adhesion of the resist pattern formed on the surface of the substrate. It is also possible to set the appropriate hydrophobic process conditions based on this relationship.
The transferring step preferably transfers the substrate subjected to the hydrophobic process to the analyzing section from the resist pattern forming apparatus in a state that the substrate is contained in an airtight container. In this case, the contaminants on the surface of the substrate during the transfer can be suppressed and the hydrophobic process state can be grasped more accurately.
According to the second aspect of the present invention, there is provided a resist pattern forming method comprising the steps of: supplying a hydrophobic process gas to a surface of a substrate to perform a hydrophobic process to the corresponding surface; coating the surface of the substrate with a resist; supplying a developing solution to the surface of the substrate subjected to exposure to light to perform developing; detecting components of the hydrophobic process gas on the surface of the substrate subjected to the hydrophobic process, whereby performing measurement of a relative detection value of the hydrophobic process gas on the surface of the substrate; and comparing a measurement result of the quantity of the hydrophobic process gas with a reference quantity of a preset quantity of the hydrophobic process gas.
According to this method, since the hydrophobic process state is monitored, it is possible to take appropriate treatments immediately when the hydrophobic process state deteriorates.
According to the third aspect of the present invention, there is provided a resist pattern forming system comprising: a hydrophobic process section for supplying a hydrophobic process gas to a surface of a substrate to perform a hydrophobic process to the corresponding surface thereof; a coating process section for coating the surface of the substrate subjected to the hydrophobic process by the hydrophobic process section with a resist; a developing process section for supplying a developing solution to the surface of the substrate, which is coated with the resist by the coating process section and which is subjected to exposure to light, to perform developing; and an analyzing section for detecting components of the hydrophobic process gas on the surface of the substrate subjected to the hydrophobic process by the coating process section, whereby performing measurement of a relative detection value of the hydrophobic process gas of the surface of the substrate.
These objects, other objects and advantages of the present invention will become readily apparent by the following description and the accompanying drawings.